Method of registering projected images



J. G. CAPSTAFF.

METHOD OF REGISTERING PROJECTED IMAGES.

APPLlCATION FILED APR-5, 1920.

1,394,504. Patented Out. 18; 1921.

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UNITED STATES PATENT OFFICE.

JOHN G. CAPSTAIFF, OF ROCHESTER, NEW YORK, ASSIGNOR TO EASTMAN KODAK COM- PANY, OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK.

METHOIO OF REGISTERING PROJECTED IZMLAGES.

Application filed April 5 To all whom it may concern:

Be it known that I, JOHN G. CAPSTAFF, a subject of the King of Great Britain, residin at Rochester, in the county of Monroe and tate of New York, have invented certain new and useful Improvements in Methods of Re istering Projected Images, of which the following is a full, clear, and exact specification.

This invention relates to a method for accurately registering two images projected from opposite directions upon a sensitized element.

It is particularly applicable in an apparatus designed for the making of a series of color records in registry upon the opposite surfaces of a long stri of double coated motion picture film, an will be described articularly with reference to such a process.

t is to be understood that there are several processes in which this may be a step, and I do not limit myself, except as my invention is defined in the appended claims, to any particular process. a

In carrying out the process described in my Patent No. 1,196,080, a master positive is made having alternating color records and from this are made by a projection printer, such as is described in British Patent No. 13,430 of 1915, on the opposite surfaces of a double coated film two series of color records in registry, all the color records of one series Specification of Letters Patent.

Patented Oct. 18, 1921.

, 1920. Serial No. 371,462.

erence will be made to the appended drawings in which the same reference characters refer to the same elements throughout, and in which:

Figure 1 is a plan partly diagrammatic and partly in section of a double projection printer;

Fig 2 is a side elevation of the same;

Fig. 3 is an end view of the mounting of a lens in one projecting system;

Fig. 4 is a side view of the same, and

Fig. 5 is a plan of a prism mountin The apparatus shown in Figs. 1 and 2 is the same (except for certain added features hereinafter described) as that shown and de-' scribed in my British patent referred to and for a complete disclosure of the details and method of use of the ap aratus reference is made to that patent. 1 indicates the double gate of a duplex film strip feeding mechanism, through which two se arate guiding mechanisms are provided. he elements of this mechanism are not shown, not being part of the invention herein claimed. It may be stated, however, that one gate aperture 5 is of the usual size correspondin to one picture area of the strip while the ot er, 4, is double the size so as to expose two picture areas at once. The film strip A, guided by rollers 2 and 3, traverses the aperture 4 and an intermittent motion of two pictures at a time is provided, while a laterally ofiset on one surface and those of the other on the but parall l film Strip at B is fed intermitother surface. These records are negative, but by the process above mentioned they are transformed into color positives, which'by transmitted 1i ht give a subtractive color rendering of t e original subject. In certain other processes positive complementary color records are printed in registry on opposite surfaces of double coated film and these are transiormed into colored images for subtractive color rendered by transmitted tently, one picture area at a step. a. Suitable reflectors, such as prisms 6 and 7 are placed on opposite sides of aperture 4 and film A, one in alinement with the upper picture exposed and the other in alinement with the lower picture exposed so as to project simultaneously the images of these latter in opposite directions along lines a and Z2, light being furnished from a common source C Beams a and?) are further projected twice at right angles through reflectmg prisms 8, 8 and lens system 9 on one side, and prisms 10, 10 and lens system 11 on the other side, until, emerging from lines a, b, respectively, they impinge from 0 p0 site directions upon the picture area of the film at B, exposed at the gate aperture 5. As the two pictures in the gate aperture 4 are vertically offset, the beams of at least one system must be so deflected that the projected images will ultimately coincide at nents of the optical systems are made adjustable. Most of the elements w1ll be perthe frame of the mac ine.

manently positioned and adjusted when the apparatus is originally set up, and will be additionally adjusted but rarely, any adj ustments necessary to the pro er reglst of any particular set of recor s being one with certain elements only. Figs. 3 and 4 show the adjustments of a. lens mounting and Fig. 5 that of a prism mounting. The horizontal corrections are made by angular movement of a prism, such as 8, which is carefully leveled on and mounted to turn with a table 20, which is adapted to rotate about a point 21. From the table 20 extend two lugs, 22 and 23, in one of which is mounted a screw 24, and the other of which carries a barrel 25, in which is mounted a in 26' pressed inwardly by a spring 27.

he screw and pin normally bear against opposite faces of a In 28 rigidly carried on Turning of the screw 24 causes rotation of the pr1sm and lateral displacement of the pro'ected image.

Vertical displacement of the image is caused by raisin or lowering the lens 9 by means of an ordinary rack and pinion 30 and 31 controlled by handwheel'32, or any other fine adjustment. Changes in magmfication are effected by moving the lens axially by means of a worm 33 engaging a suitable rack or thread 34, and actuated by handwheel 35. This slight change necessary to alter magnification is not sufiicient to disturb the focus of thesystem materially. The mechanical movements noted are not important as obviously others can be substituted therefor. Lens 11 may have similar adjustments.

At a suitable point in each projecting system I insert a color filter or screen 50, 51. In the processes to which this invention is applicable the color records are taken through complementary filters, which I will designate as red and green. The red color record is -ultimately colored minus-red and the green color record is colored minus-green, since the projection of the completed film is a subtractive rocess. By the terms red and green, mean records that are complementary, the prevailing colors being red and green. The filters 50 and 51 are, however, preferably similar to those through which the records were taken. At the exposure gate I now place a translucent color screen without any prevailing color tone. This is placed at identically the plane B customarily OCCIiPlGd by the double coated film. As a screen employ preferably a piece of transparent pyroxylin coated on one surface with a thin coating of a fine grained gelatin from the colored double coated film. This additive color record permits a very fine standard of registration to be attained. Very slight imperfections of registration are at once visible as color fringes or lines of color bounding the objects or pictures, and these are distinctly visible where lack of registry could not be detected by other means of examining su rposed images. In order to attain the big est possible accuracy, I mount at a suitable point a telescope 60 through which the screen may chine are unimportant and that the arrangement of the picture areas on the projected film at A may be varied by malcing such suitable changes in the gate as could be made by a competent designer.

Having thus described my invention, what I claim as newrand desire to secure by Letters Patent is: 3

1. The method of perfecting the registration of two ima es of the same subject projected through independent optical systems and superposed from opposite directions upon the same exposure and focusing plane that consists of insertin' in said plane a focusing screen upon whic projected images are visible by reflected and by transmitted light, inserting into said optical systems con- .trasting. color filters whereby additive color images are projected on said screen from opposite sides, examining said additive images, one by reflected and one b transmit-= ted light,'upon said screen for t e presence of color fringes caused by imperfect'registration and relatively adjustirg said optical systems to correct such imperfect registration.

2. The method of perfectin the registration of the. images of two co or records of the same subject projected through independent optical systems and superposed from opposite directions upon the same e re and focusin plane that consists of mserting in sal plane a translucent focusing screen upon w ch projected ima are visible by reflected or transmitted light, insertin into said optical systems complementary 00 or filters similar to those by means of belexamined. It is to be understood that the details of the ma-.

which the color records were produced so that additive color images are projected on said screen from opposite sides, examining said additive color images, one b transmitted light and one by reflected lig t, upon said screen for the presence of color fringes caused by imperfect registration and adjusting one of said optical systems to correct any such imperfect registration and remove the color frin es.

Signed at ochester, day of March, 1920.

JOHN cArsTAFF.

10 New York, this 27th 

